Understanding the nature of the plasmon modes in noble metal nanostructures is of vital importance because different plasmon modes exhibit distinct optical properties, which in turn determine their plasmon-based applications. We have systematically studied the evolution and nature of the different plasmon modes in (Au core)/(Ag shell) nanorods. The plasmonic properties of the nanorods are essentially determined by the Ag shell and are tunable by synthetically changing the core size and shell thickness. With increasing shell thicknesses, four plasmon bands are observed. They are ascribed to the longitudinal dipolar mode, transverse dipolar mode, and two octupolar modes, respectively, in the order of decreasing plasmon wavelengths. The plasmon wavelengths and intensities of the four modes vary gradually versus the shell thickness. The retardation effect and the interference between the excitations are crucial for exciting the two octupolar modes. Our results are useful for designing (Au core)/(Ag shell) nanostructures and utilizing their attractive and rich plasmonic properties for various plasmonic applications.

Unraveling the evolution and nature of the plasmons in (Au core)/(Ag shell) nanorods

245th National Meeting (2013)

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